Method for manufacturing crankshafts

ABSTRACT

A method for manufacturing abrasion-resistant crankshafts including: first, forming a plurality of abrasion-resistant cam rings from an abrasion-resistant material such as a steel alloy of high chrome iron-carbide; placing the abrasion-resistant cam rings in a mold set on desired locations; pouring a melting metal formed by FCD45 high flexible-resistant cast iron into the mold set to form a shaft portion to couple with the abrasion-resistant cam rings; and solidifying the melting metal to become a crankshaft that is abrasion-resistant and flexible-resistant. The crankshaft thus formed can be used in heavy duty and severe conditions without wearing and fracturing.

FIELD OF THE INVENTION

The present invention relates to crankshafts and more particularly to a method for manufacturing crankshafts.

BACKGROUND OF THE INVENTION

A crankshaft is an important element to output diving power of vehicle engines. The conventional method for manufacturing crankshafts generally includes forming a cavity in the shape of a crankshaft in a mold set resistant to high temperature; then pouring a melting metal into the cavity that is cooled and solidified to form a crankshaft; and the cams of the crankshaft are machining by grinding to form the finished crankshaft of the vehicle engine.

Most known vehicle manufacturers in the world fabricate the crankshafts for the engines by chill casting or from FCD700 materials. The lower shaft made from the FC material by chill casting is easily ruptured when used in heavy loading or severe conditions. The FCD700 materials cannot withstand high temperature, and abrasion wearing occurs after used for a period of time. As a result, the engine power diminishes, and noise occurs. Replacement has to be done periodically. It is costly. In view of the foregoing concerns, the present invention aims to provide an abrasion-resistant and more permanently durable crankshaft to meet market requirements.

SUMMARY OF THE INVENTION

Therefore the primary object of the present invention is to provide a method for manufacturing crankshafts that have a greater abrasion-resistance and precision without increasing cost.

The method for manufacturing crankshafts of the invention aims to fabricate a crankshaft. The crankshaft has a shaft portion and a plurality of abrasion-resistant cam rings. The method includes the steps of:

First, fabricate a plurality of the abrasion-resistant cam rings by casting. Each of the abrasion-resistant cam rings has an aperture.

Next, fabricate a mold set which consists of two mold elements coupled together to form a casting orifice. The mold set has a housing chamber formed in the shape of the crankshaft communicating with the casting orifice.

Place the abrasion-resistant cam rings in the housing chamber of the mold set.

Pour a melting metal formed by a FCD45 high flexible-resistant cast iron into the mold set through the casting orifice to fill the apertures of the abrasion-resistant cam rings to form the shaft portion.

Finally, solidify the melting metal and remove the rough blank of the crankshaft from the mold set.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the crankshaft of the present invention.

FIG. 2 is a manufacturing process flow of the present invention.

FIG. 3 is a schematic view of the abrasion-resistant cam ring of the present invention.

FIG. 4 is a schematic view of a mold set of the present invention.

FIG. 5 is a schematic view of placing the abrasion-resistant cam ring in the mold set according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please referring to FIGS. 1 through 5, the method for manufacturing crankshafts according to the invention aims to fabricate a crankshaft 10. The crankshaft 10 includes a shaft portion 20 made from a FCD45 high flexible-resistant casting iron and a plurality of abrasion-resistant cam rings 30 made from a steel alloy of high chrome iron-carbide. The manufacturing method includes steps 2A-2E as follow:

Step 2A: Fabricate the abrasion-resistant cam rings 30 each has an aperture 301.

Step 2B: Fabricate a mold set 40 which consists of two mold elements 401 that are coupled together to form a casting orifice 402. The mold set 40 has a housing chamber 403 formed according to the crankshaft 10. The housing chamber 403 communicates with the casting orifice 402.

Step 2C: Place the abrasion-resistant cam rings 30 in the housing chamber 403 of the mold set 40.

Step 2D: Pour a melting metal (not shown in the drawings) formed by a FCD45 high flexible-resistant cast iron into the mold set 40 through the casting orifice 402 to fill the apertures 301 of the abrasion-resistant cam rings 30 to form the shaft portion 20.

Step 2E: Solidify the melting metal and remove the rough blank of the crankshaft 10 from the mold set 40.

In the crankshaft 10 fabricated according to the method of the invention previously discussed, each of the abrasion-resistant cam rings 30 may have a positioning boss 302. The housing chamber 403 has a plurality of cavities 404 corresponding to the positioning bosses 302 so that the abrasion-resistant cam rings 30 may be placed in the housing chamber 403 of the mold set 40 on precise locations. After the rough blank of the crankshaft 10 is produced, the bosses 302 may be removed by grinding.

The material used in fabricating the abrasion-resistant cam rings 30 of the invention is a steel alloy such as high chrome iron-carbide that is abrasion-resistant and can withstand the high temperature of the melting metal without lowering the hardness. The shaft portion 20 is made by melting FCD45 high flexible-resistant cast iron. The crankshaft 10 thus formed is made from two types of materials, in which the material of the abrasion-resistant cam rings 30 (steel alloy of high chrome iron-carbide) can withstand abrasion wearing, and the material of the shaft portion 20 (FCD45 high flexible-resistant cast iron) can facilitate machining with a high flexibility without fracturing. The manufacturing method of the invention makes machining easier without increasing the cost, and the cams can be permanently durable without wearing. The shaft portion 20 can be used safely even in the heavy duty and severe conditions to maintain the engine in an optimum performance condition. It can save a lot of cost for consumers, and the product is more competitive in the market place. 

1. A method for manufacturing crankshafts to fabricate a crankshaft which has a flexible-resistant shaft portion to facilitate machining and a plurality of abrasion-resistant cam rings, the method comprising the steps of: fabricating the abrasion-resistant cam rings each having an aperture; fabricating a mold set which consists of two mold elements coupled together to form a casting orifice, the mold set has a housing chamber formed according to the crankshaft that communicates with the casting orifice; placing the abrasion-resistant cam rings in the housing chamber of the mold set on desired locations; pouring a melting metal into the mold set through the casting orifice to fill the apertures of the abrasion-resistant cam rings to form the shaft portion; and solidifying the melting metal and removing the crankshaft from the mold set.
 2. The method of claim 1, wherein each of the abrasion-resistant cam rings has a positioning boss, the housing chamber having a plurality of cavities corresponding to the positioning bosses to allow the abrasion-resistant cam rings to be positioned on desired locations, the positioning bosses being removed by grinding after the crankshaft has been removed from the mold set.
 3. The method of claim 1, wherein the abrasion-resistant cam rings are made from a high abrasion-resistant material.
 4. The method of claim 3, wherein the abrasion-resistant cam rings are made from a steel alloy of a high chrome iron-carbide.
 5. The method of claim 1, wherein the melting metal is FCD45 high flexible-resistant cast iron. 